ORIGINAL RESEARCH published: 18 September 2019 doi: 10.3389/fnhum.2019.00321 Edited by: Francesco Di Russo, Foro Italico University of Rome, Italy Reviewed by: Keiko Ogawa, Hiroshima University, Japan Paolo Gargiulo, Landspitali University Hospital, Iceland *Correspondence: Silvia Comani comani@unich.it Specialty section: This article was submitted to Brain Imaging and Stimulation, a section of the journal Frontiers in Human Neuroscience Received: 14 May 2019 Accepted: 02 September 2019 Published: 18 September 2019 Citation: Stone DB, Tamburro G, Filho E, di Fronso S, Robazza C, Bertollo M and Comani S (2019) Hyperscanning of Interactive Juggling: Expertise Influence on Source Level Functional Connectivity. Front. Hum. Neurosci. 13:321. doi: 10.3389/fnhum.2019.00321 Hyperscanning of Interactive Juggling: Expertise Influence on Source Level Functional Connectivity David B. Stone 1,2 , Gabriella Tamburro 1,2 , Edson Filho 3 , Selenia di Fronso 1,4 , Claudio Robazza 1,4 , Maurizio Bertollo 1,4 and Silvia Comani 1,2 * 1 BIND – Behavioral Imaging and Neural Dynamics Center, University “G. d’Annunzio” of Chieti-Pescara, Chieti, Italy, 2 Department of Neuroscience, Imaging and Clinical Sciences, University “G. d’Annunzio” of Chieti-Pescara, Chieti, Italy, 3 SINAPSE – Social Interaction and Performance Science Laboratory, School of Psychology, University of Central Lancashire, Preston, United Kingdom, 4 Department of Medicine and Aging Sciences, University “G. d’Annunzio” of Chieti-Pescara, Chieti, Italy Hyperscanning studies, wherein brain activity is recorded from multiple participants simultaneously, offer an opportunity to investigate interpersonal dynamics during interactive tasks at the neurophysiological level. In this study, we employed a dyadic juggling paradigm and electroencephalography (EEG) hyperscanning to evaluate functional connectivity between EEG sources within and between jugglers’ brains during individual and interactive juggling. We applied graph theoretical measures to identify significant differences in functional connectivity between the individual and interactive juggling conditions. Connectivity was measured in multiple juggler pairs with various skill levels where dyads were either skill-level matched or skill-level unmatched. We observed that global efficiency was reduced during paired juggling for less skilled jugglers and increased for more skilled jugglers. When jugglers were skill-level matched, additional reductions were found in the mean clustering coefficient and small-world topology during interactive juggling. A significant difference in hemispheric brain lateralization was detected between skill-level matched and skill-level unmatched jugglers during interactive juggling: matched jugglers had an increased right hemisphere lateralization while unmatched jugglers had an increased left hemisphere lateralization. These results reveal multiple differences in functional brain networks during individual and interactive juggling and suggest that similarities and disparities in individual skills can impact inter-brain dynamics in the performance and learning of motor tasks. Keywords: hyperscanning, EEG, interactive juggling, graph theory, skill-level INTRODUCTION Juggling is a unique and complex skill that depends on multiple perceptual-motor and cognitive abilities and processes including coordination, visuo-spatial attention, motor vigilance, performance related self-monitoring, and sensorimotor learning (Sánchez García et al., 2013; Rodrigues et al., 2016). Advances in neuroimaging, which permit the acquisition of brain data in Frontiers in Human Neuroscience | www.frontiersin.org 1 September 2019 | Volume 13 | Article 321